Gz compress images



  • Running the shop in Goögle pagespeed suggest to use GZ compression of the images. Is someone using this? Any difference?


  • Global Moderator

    Pictures are already compressed (exception: some vintage formats like BMP). Compressing them twice can make them actually larger:

    $ ll test.png
    -rw-r--r-- 1 user user 2879672 Mai 13 11:08 test.png
    $ gzip test.png 
    $ ll test.png.gz 
    -rw-r--r-- 1 user user 2880128 Mai 13 11:08 test.png.gz
    


  • Insight claim my png should be 77% smaller



  • It might be that the images on your pages could use a “lower” JPEG image quality setting without much if any impact on the resulting image quality. Google talks about this a bit here:
    https://developers.google.com/speed/docs/insights/OptimizeImages

    Edit: Looking at the site linked in your signature I don’t think there are any gains to be made from additional compression. There is already jpeg artifacting in the images I looked at, and they aren’t excessively large images or anything like that either. Maybe the recommendation was for a few specific images on your site?



  • In my case, I use gimp save for web to get best images size



  • That is not an option in my case. I never have the pictures, I upload them to the web server directly from the supplier



  • Oh I see, I think you can try www.resmush.it , but I can’t confirm the result as you expected



  • I think my edit was too late to be seen before you replied, @Havouza.

    I had a look at the images on your site and they are already very compressed. Perhaps over compressed as there is quite a lot of jpeg artifacting in some of them. (I know this isn’t your choice as you get the images from your supplier.)

    In the future (for a different site, perhaps) if you do need to re-compress images in batches you can automate this with a simple script for ImageMagick. I automate the resizing and watermarking of all my images with ImageMagick and once it’s set up it’s such a huge time saver.



  • I will make you do that for the next one ;-)
    The uppload from supplier comes as a zip which I download and uszip using a cron every Saturday. The import module then pick them there. In the db I have the full URL and the developer explained that the images get resized when called first time



  • @Havouza said in Gz compress images:

    Insight claim my png should be 77% smaller

    I missed this message earlier somehow, and what they say is very possible.

    PNG is a lossless image file format. It has very good compression but without using special trickery the files will always be much larger than JPG files with similar image quality. If you find those PNG files and convert them to JPG they will be much smaller.


  • Global Moderator

    [PNG] has very good compression but without using special trickery the files will always be much larger than JPG files with similar image quality.

    Depends a lot on the type of image. For photographs, JPEGs are typically smaller, that’s true. Graphics with sharp boundaries and larger areas of the exactly same color, e.g. a page of text or screenshots, compress a lot better with PNG.



  • I should’ve been clearer that I was only talking about product photos, the types of photos that are typically used on eCommerce websites.


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